1. Field of the Invention
The invention relates to a sapphire protective covering for the distal end of endoscopes, which distal end is outfitted with an optical system and glass fibers serving to illuminate the viewing field. The sapphire protective covering substantially contains an optical tube holding the optical lens fittings or mountings, an inner tube receiving the optical tube, and an outer tube enclosing the optical tube, inner tube and glass fibers.
2. Description of the Related Art
Depending on the optical requirements imposed on an endoscope, e.g. with respect to the degree of the viewing angle, straight or angled view, etc., the distal end can be constructed so as to be beveled or at a right angle to the longitudinal axis of the endoscope.
Such endoscopes are used in areas of medicine such as arthroscopy in which it comes about time and again that the operating doctor, when removing cartilage and/or bone fragments, cuts into the tip of the endoscope with the inserted rotating instruments and damages the optical system and also the ends of the glass fibers located in this area. As a result of damage to the optical system, the operating doctor immediately loses the image of the operating field in part or in its entirety and may have to interrupt the operation.
To prevent damage to the outlet surface or exit area of the optical system it is known to provide substantially more resistant, i.e. harder, protective coverings manufactured particularly from sapphire.
The disadvantage in such protective coverings consists in that they either only protect the optical lens system or, to the extent that they simultaneously cover the ends of the glass fibers as well, cause light to be reflected into the optical system from the ends of the glass fibers which handicaps the user in such a way that he cannot clearly perceive the objects to be viewed through the optical system.